<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <script src="/js/spritejs.js"></script>
  <script src="//lib.baomitu.com/dat-gui/0.7.2/dat.gui.min.js"></script>
  <style>
    #adaptive {
      width: 100%;
      padding-bottom: 50%;
      background: #eee;
    }
  </style>
</head>
<body>
  <div id="adaptive"></div>
  <script>
    const {Scene, Path, Sprite, Gradient} = spritejs;
    const container = document.getElementById('adaptive');
    const scene = new Scene({
      container,
      width: 1200,
      height: 600,
      // contextType: '2d',
    });
    const layer = scene.layer();

    const birdsJsonUrl = 'https://s5.ssl.qhres.com/static/5f6911b7b91c88da.json';
    const birdsRes = 'https://p.ssl.qhimg.com/d/inn/c886d09f/birds.png';

    (async function () {
      await scene.preload([birdsRes, birdsJsonUrl]);
      const d = 'M480,437l-29-26.4c-103-93.4-171-155-171-230.6c0-61.6,48.4-110,110-110c34.8,0,68.2,16.2,90,41.8C501.8,86.2,535.2,70,570,70c61.6,0,110,48.4,110,110c0,75.6-68,137.2-171,230.8L480,437Z';

      const gradient = new Gradient({
        vector: [280, 470, 680, 70],
        colors: [{
          offset: 0,
          color: 'rgba(255,0,0,1)',
        }, {
          offset: 0.5,
          color: 'rgba(255,0,0,0)',
        }, {
          offset: 1,
          color: 'rgba(255,0,0,0)',
        }],
      });

      const path = new Path({
        d,
        lineWidth: 26,
        fillColor: 'red',
        strokeColor: gradient,
        // lineJoin: 'bevel',
      });

      layer.append(path);
      window.path = path;

      const bird = new Sprite('bird1.png');
      bird.attr({
        anchor: [0.5, 0.5],
        size: [65, 45],
        offsetPath: d,
        zIndex: 200,
      });

      layer.append(bird);

      bird.animate([
        {offsetDistance: 0},
        {offsetDistance: 1},
      ], {
        duration: 6000,
        iterations: Infinity,
      });

      let i = 0;
      setInterval(() => {
        bird.attributes.texture = `bird${i++ % 3 + 1}.png`;
      }, 100);

      const startTime = Date.now();
      const T = 6000;
      requestAnimationFrame(function next() {
        const p = Math.PI * 2 * (Date.now() - startTime) / T;
        const colors = [
          {offset: 0, color: 'rgba(255,0,0,1)'},
          {offset: 0.5 + 0.5 * Math.abs(Math.sin(p)), color: 'rgba(255,0,0,0)'},
          {offset: 1, color: 'rgba(255,0,0,0)'},
        ];

        const gradients = new Gradient({
          vector: [280, 470, 680, 70],
          colors,
        });
        path.attr({strokeColor: gradients});

        requestAnimationFrame(next);
      });
    }());
  </script>
</body>
</html>
